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See detailA mathematical model of actin filament turnover for fitting FRAP data
Halavatyi, A. A.; Nazarov, P. V.; Al Tanoury, Z. et al

in European Biophysics Journal [=EBJ] (2010), 39(4), 669-677

A novel mathematical model of the actin dynamics in living cells under steady-state conditions has been developed for fluorescence recovery after photobleaching (FRAP) experiments. As opposed to other ... [more ▼]

A novel mathematical model of the actin dynamics in living cells under steady-state conditions has been developed for fluorescence recovery after photobleaching (FRAP) experiments. As opposed to other FRAP fitting models, which use the average lifetime of actins in filaments and the actin turnover rate as fitting parameters, our model operates with unbiased actin association/dissociation rate constants and accounts for the filament length. The mathematical formalism is based on a system of stochastic differential equations. The derived equations were validated on synthetic theoretical data generated by a stochastic simulation algorithm adapted for the simulation of FRAP experiments. Consistent with experimental findings, the results of this work showed that (1) fluorescence recovery is a function of the average filament length, (2) the F-actin turnover and the FRAP are accelerated in the presence of actin nucleating proteins, (3) the FRAP curves may exhibit both a linear and non-linear behaviour depending on the parameters of actin polymerisation, and (4) our model resulted in more accurate parameter estimations of actin dynamics as compared with other FRAP fitting models. Additionally, we provide a computational tool that integrates the model and that can be used for interpretation of FRAP data on actin cytoskeleton. © 2009 European Biophysical Societies' Association. [less ▲]

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See detailA mathematical model of metabolism and regulation provides a systems-level view of how Escherichia coli responds to oxygen
Ederer, M; Steinsiek, S; Stagge, S et al

in Frontiers in Microbiology (2014), 5(124),

The efficient redesign of bacteria for biotechnological purposes, such as biofuel production, waste disposal or specific biocatalytic functions, requires a quantitative systems-level understanding of ... [more ▼]

The efficient redesign of bacteria for biotechnological purposes, such as biofuel production, waste disposal or specific biocatalytic functions, requires a quantitative systems-level understanding of energy supply, carbon, and redox metabolism. The measurement of transcript levels, metabolite concentrations and metabolic fluxes per se gives an incomplete picture. An appreciation of the interdependencies between the different measurement values is essential for systems-level understanding. Mathematical modeling has the potential to provide a coherent and quantitative description of the interplay between gene expression, metabolite concentrations, and metabolic fluxes. Escherichia coli undergoes major adaptations in central metabolism when the availability of oxygen changes. Thus, an integrated description of the oxygen response provides a benchmark of our understanding of carbon, energy, and redox metabolism. We present the first comprehensive model of the central metabolism of E. coli that describes steady-state metabolism at different levels of oxygen availability. Variables of the model are metabolite concentrations, gene expression levels, transcription factor activities, metabolic fluxes, and biomass concentration. We analyze the model with respect to the production capabilities of central metabolism of E. coli. In particular, we predict how precursor and biomass concentration are affected by product formation. - See more at: http://journal.frontiersin.org/Journal/10.3389/fmicb.2014.00124/abstract#sthash.Ocu5zSDe.dpuf [less ▲]

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See detailMathematical modeling of the central carbohydrate metabolism in Arabidopsis reveals a substantial regulatory influence of vacuolar invertase on whole plant carbon metabolism.
Nagele, Thomas; Henkel, Sebastian; Hormiller, Imke et al

in Plant Physiology (2010), 153(1), 260-72

A mathematical model representing metabolite interconversions in the central carbohydrate metabolism of Arabidopsis (Arabidopsis thaliana) was developed to simulate the diurnal dynamics of primary carbon ... [more ▼]

A mathematical model representing metabolite interconversions in the central carbohydrate metabolism of Arabidopsis (Arabidopsis thaliana) was developed to simulate the diurnal dynamics of primary carbon metabolism in a photosynthetically active plant leaf. The model groups enzymatic steps of central carbohydrate metabolism into blocks of interconverting reactions that link easily measurable quantities like CO(2) exchange and quasi-steady-state levels of soluble sugars and starch. When metabolite levels that fluctuate over diurnal cycles are used as a basic condition for simulation, turnover rates for the interconverting reactions can be calculated that approximate measured metabolite dynamics and yield kinetic parameters of interconverting reactions. We used experimental data for Arabidopsis wild-type plants, accession Columbia, and a mutant defective in vacuolar invertase, AtbetaFruct4, as input data. Reducing invertase activity to mutant levels in the wild-type model led to a correct prediction of increased sucrose levels. However, additional changes were needed to correctly simulate levels of hexoses and sugar phosphates, indicating that invertase knockout causes subsequent changes in other enzymatic parameters. Reduction of invertase activity caused a decline in photosynthesis and export of reduced carbon to associated metabolic pathways and sink organs (e.g. roots), which is in agreement with the reported contribution of vacuolar invertase to sink strength. According to model parameters, there is a role for invertase in leaves, where futile cycling of sucrose appears to have a buffering effect on the pools of sucrose, hexoses, and sugar phosphates. Our data demonstrate that modeling complex metabolic pathways is a useful tool to study the significance of single enzyme activities in complex, nonintuitive networks. [less ▲]

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See detailMathematical Modelling of Flux Decline due to Concentration Polarisation and Cake Layer Formation in Crossflow Filtration Systems
Hale, Jack UL; Li, Qilin; Harris, Alison et al

Scientific Conference (2007, May)

Crossflow membrane filtration is an effective way of removing both colloidal and dissolved organic matter from contaminated water supplies. Two phenomena domimate solute flux in crossflow systems ... [more ▼]

Crossflow membrane filtration is an effective way of removing both colloidal and dissolved organic matter from contaminated water supplies. Two phenomena domimate solute flux in crossflow systems; concentration polarization and cake layer formation. Many innovative mathematical models for predicting both flux decline and quasi-steady state flux have been produced in the literature. However, limited regime applicability and conflicting physical predictions have made choosing optimal performance parameters in design a challenging process. An overview of the current field of models was undertaken, including an assessment of mathematical assumptions, numerical computation workload and number and complexity of system constants. A new model incorporating viscosity dependence on concentration is developed for the concentration polarization regime. Preliminary results will also be presented from a Monte Carlo based molecular dynamics simulation of volume packing fraction in the cake layer regime. The novel aspects of these models will be compared with existing models and the experimental results of our collaborators. Laboratory ultrafiltration tests were undertaken using varying concentrations of Dextran. An outline of future model directions and refinements will be presented. [less ▲]

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See detailMathematical Modelling of Network Traffic
Li, Yu UL

Doctoral thesis (2015)

ncreasing access to the Internet is producing profound influence around the World. More and more people are taking advantage of the Internet to obtain information, communicate with each other far away and ... [more ▼]

ncreasing access to the Internet is producing profound influence around the World. More and more people are taking advantage of the Internet to obtain information, communicate with each other far away and enjoy various recreations. This largely increased demand for the Internet requires better and more effective models. During the 1990s, a number of studies show that due to a different nature from telephonic traffic, in particular a bursty nature, traditional queuing models are not applicable in modeling of modern traffic. This work presents some alternative rigorous models that can be used in studying the behavior of the Internet traffic. In the thesis, we propose several new models to explain bursty nature of network traffic. Many practical problems in computer science, natural science and insurance are highly complex, since they typically involve a huge amount of random factors. Con- ventional queuing theory cannot handle such problems and the high variance and long memory features are not yet well understood. In the first part of our research, we start with investigation of random sum as well as random product and derive a single path model of network traffic and a multiple path model of network traffic.In the second part of this thesis, we present a homotopic approach to model network traffic. [less ▲]

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See detailMathematical modelling of the Platelet-Derived Growth Factor (PDGF) signalling pathway
Mizera, Andrzej UL; Pang, Jun UL; Sauter, Thomas UL et al

in Proceedings of 4th Workshop on Computational Models for Cell Processes (CompMod'13) (2013)

Detailed reference viewed: 100 (10 UL)
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See detailMathematical models and social representation
Valsiner, Jaan UL

in Rudolph, Lee (Ed.) Qualitative mathematics for the social sciences (2013)

Detailed reference viewed: 26 (0 UL)
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See detailMathematical models of circadian Ca2+ oscillations
Neil, D.; Goncalves, Jorge UL; Webb, A.R.

in Proceedings of the eighth International Conference on Systems Biology (2007)

In the model plant Arabidopsis thaliana, the concentration of cytosolic-free Ca2+ ([Ca2+]cyt) oscillates with a circadian rhythm. We are investigating the regulation and role of these oscillations both ... [more ▼]

In the model plant Arabidopsis thaliana, the concentration of cytosolic-free Ca2+ ([Ca2+]cyt) oscillates with a circadian rhythm. We are investigating the regulation and role of these oscillations both experimentally and mathematically. Through systems identification, we have developed simple mathematical models from a single experiment measuring [Ca2+]cyt and the promoter activity of CIRCADIAN CLOCK ASSOCIATED 1 (CCA1). Through validation with 4 contrasting datasets, including a clock-arrhythmic transgenic line (CCA1 overexpressor), we demonstrate the necessity for a light input pathway to regulate basal [Ca2+]cyt levels. [less ▲]

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See detailMathematical relationships between representations of structure in linear interconnected dynamical systems
Yeung, E.; Goncalves, Jorge UL; Sandberg, H. et al

in The proceedings of the 2011 American Control Conference (ACC) (2011)

A dynamical system can exhibit structure on multiple levels. Different system representations can capture different elements of a dynamical system's structure. We consider LTI input-output dynamical ... [more ▼]

A dynamical system can exhibit structure on multiple levels. Different system representations can capture different elements of a dynamical system's structure. We consider LTI input-output dynamical systems and present four representations of structure: complete computational structure, subsystem structure, signal structure, and input output sparsity structure. We then explore some of the mathematical relation ships that relate these different representations of structure. In particular, we show that signal and subsystem structure are fundamentally different ways of representing system structure. A signal structure does not always specify a unique subsystem structure nor does subsystem structure always specify a unique signal structure. We illustrate these concepts with a numerical example. [less ▲]

Detailed reference viewed: 106 (2 UL)
See detailMathematician - Job of the Year 2014
Poncin, Norbert UL

Speeches/Talks (2015)

Detailed reference viewed: 71 (9 UL)
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See detailMathematics - Professional Prospects
Poncin, Norbert UL

Conference given outside the academic context (2016)

Detailed reference viewed: 88 (5 UL)
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See detailThe mathematics behind the property of associativity
Marichal, Jean-Luc UL; Teheux, Bruno UL

in De Baets, Bernard; Mesiar, Radko; Saminger-Platz, Susanne (Eds.) et al 36th Linz Seminar on Fuzzy Set Theory (LINZ 2016) - Functional Equations and Inequalities (2016, February)

The well-known equation of associativity for binary operations may be naturally generalized to variadic operations. In this talk, we illustrate different approaches that can be considered to study this ... [more ▼]

The well-known equation of associativity for binary operations may be naturally generalized to variadic operations. In this talk, we illustrate different approaches that can be considered to study this extension of associativity, as well as some of its generalizations and variants, including barycentric associativity and preassociativity. [less ▲]

Detailed reference viewed: 86 (7 UL)
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See detailMathematics teacher development and technology: towards an International GeoGebra Institute
Hohenwarter, Markus; Hohenwarter, Judith; Kreis, Yves UL et al

Poster (2008, July 09)

Research indicates that despite the numerous benefits of using technology in mathematics education, the process of embedding technology in classrooms is slow and complex. Most teachers need more than just ... [more ▼]

Research indicates that despite the numerous benefits of using technology in mathematics education, the process of embedding technology in classrooms is slow and complex. Most teachers need more than just being provided with technology if the benefits of technology are to be substantially realized. It has been suggested that adequate training and collegial support boost teachers' willingness to integrate technology into their teaching and to develop successful technology-assisted teaching practices. GeoGebra is free open-source dynamic software for mathematics teaching and learning that offers geometry and algebra features in a fully connected software environment. Its pool of free interactive materials and user forum are examples of online collaboration of a world-wide community of mathematics educators. In this poster presentation, we will outline the emergence of the software GeoGebra and its recent developments as well as the first steps towards (using present tense to show that work has already been done) International GeoGebra Institute to be able to offer structured training and support for teachers who are ready to integrate GeoGebra into their classrooms. In addition, we will organize and coordinate research projects in relation to GeoGebra to enhance the development of training and support materials. While our initial plan is to establish an IGI site at Florida Atlantic University (USA), in the long run our goal is to collaborate with colleagues and set up other institutes in various locations around the world. [less ▲]

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See detailMathematik als universeller Schluessel komplexer Systeme
Schlichenmaier, Martin UL

Speeches/Talks (2016)

Detailed reference viewed: 35 (3 UL)
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See detailMathématique physique 1 et 2
Poncin, Norbert UL

Learning material (2008)

Detailed reference viewed: 92 (4 UL)
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See detailMathématique physique 3
Poncin, Norbert UL

Learning material (2008)

Detailed reference viewed: 106 (9 UL)
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See detailMathis Leibetseder: Die Kavalierstour. Adelige Erziehungsreisen im 17. und 18. Jahrhundert
Tröhler, Daniel UL

in Zeitschrift für Pädagogik (2005), 51

Detailed reference viewed: 103 (0 UL)
See detailMatinée with Carlo Ghezzi - from Programming Languages to Software Engineering
Bianculli, Domenico UL; Jazayeri, Mehdi; Pezzè, Mauro

Book published by CreateSpace (2012)

Detailed reference viewed: 103 (3 UL)